Attitude and range determining system



represented by Secretary of the Navy 511 Int.Cl. nous/3o United StatesPatent [1113,546,376

72] Inventors John D. Creeelius [50] Field ofSeareh 178/6.8, m; 6(lND),6(Trackers); 343/(lnquired), 5(MM), William A. Arriola; Howard l.Smnnicht; 6(TV) fig ff g [56] References Cited [2]] Appl. No. 701,930UNITED STATES PATENTS [22] Filed Jan. 31, 1968 3,120,578 2/ 1964 Potteret al. l78/6.8

[45] Patented Dec. 8, 1970 Prim ary Exammer-Robert L. Griffin [73]Assignee the United States of America as Assistant Examiner Richar-d K.Ecken, Jr.

Attorney-George J. Rubens, Roy Miller and Victor Muller ABSTRACT: Amethod of determining the orientation of an object in flight wherein thetelevision image of a scale model of the object of interest and atelevision image of the filmed record of the same object aresuperimposed by rotating the model until the orientation of the scalemodel matches that of the filmed record.

PATENTEU DEC-8 I970 X SCANNER gcgg --'l-TRANSLATOR fgfi'fifil I 32 33 I4a 6l 49 I f 30 FIG. 2.

l8 45$ T,46 50 /I3 MODEL MODEL TELEVISION CAMERA CAMERA g CONTROL I 5|/l4 1e 55 2 I MONITOR 1\\ INVENTORS, I JOHN D. CRECELIUS TARGET TARGET52 WILLIAM A. ARRIOLA a g ga O- 53 HOWARD I. SUMNICHT A L 54 EPHRAIMREGELSON GEORGE 0. SILBERBERG ROY MILLER ATTORNEY.

1 ATTITUDE AND RANGE DETERMINING SYSTEM BACKGROUND OF THE INVENTION Inassessing the filmed flight of a moving target it is desirable todetermine the instantaneous slant range, azimuth and elevation angles ofthe filmed target relative to the position of the camera at the time ofthe filming.

In filming the flight of a moving target the tracking film is not ableto record the image of the target in a standard aspect.

When evaluating the tracking film frame by frame, projective geometrymust be used to rectify the image so that a known main dimension, suchas a wing span or fusilage length, is at a right angle to the viewer.Comparison of the rectified image dimension with the actual dimensionyields the target slant range. Such a technique'will work, however theprocess is laborious and slow. I

It is conceptually feasible to computerize projective geometrytechniques. Such a system would have to be highly sophisticated andcomplex due to the fact that the rectification of the picture must bedone on a point-to-point basis. A human eye, which can discriminate onetenth of a degree change between line movements, makes the idea ofoptical attitude recognition attractive.

SUMMARY OF THE INVENTION In accordance with the present invention, thefilmed image of a moving target is projected on a translucent screen. Afirst television camera records the image of the screen and feeds thedata to a television monitor. A second television camera views a smallscale model of the target. The small scale model is capableof beingrotated about two axes, the first corresponding to azimuth and thesecondcorresponding to elevation. The television camera-viewing the model iscapable of movement toward or away" from the model. The position of themodel, with respect to the television camera, is arranged to be read outdirectly in range, azimuth and elevation. At the position correspondingto superimposition the range, azimuth and elevation of the modelcorrespond directly to the range, azimuth and elevation of a movingtarget with respect to a given camera.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective'view'partially in block diagram form of a preferred embodiment of theinvention;

FIG. 2 is a block diagram of the means for reading out range, azimuthand elevation", and

FIG. 3 is a block diagram of the mixer shown in FIG. .1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, a movieprojector projects an image of a moving target on to screen 11. Targettelevision camera 12 views the image and transmits it electronicallyover data link 15 to mixer 13. The speed and direction at which the filmmoves through projector 10 and the intensity of the light source locatedwithin projector 10 may be controlled from control panel 57 bycontrolling means 42. During each data determination sequence the filmpassing through projector 10 is held stationary on'a preselected framewhich is of interest.

Model television camera 18 views a scale model 19 through zoom lens 58and also transmits the picture received to mixer 13 over data link 16.As shown in FIG. 3, model television camera 18 is operatively connectedto model camera control to the position 'of the image received by targettelevision camera 12.

Airplane model 19 is mounted so that its axes of rotation are centeredabout its tail section. Rotation of model 19 in direction 20 correspondsto a change in elevation which may be read out by elevation digitalencoder 22. Rotation of model 19 in direction 21 corresponds to a changein azimuth which may be read out by azimuth digital encoder 23. Itshould be 55 by data link 16 and target television camera 12 is opera- Inoted that encoders 22 and 23 may be replaced by potentiometers or anyother suitable angular position measuring means.

Television camera 18 is mounted on a rail 24 by means of a supportbracket 59 and is moved toward or away from scale model 19 in direction27 by means of a cog belt 29 driven by a motor 28. Motor 28 is activatedby range control 40 via data link 35. Camera 18, with zoom lens 58mounted thereon, is rotatable in direction 25 about its optical axis.Lens 58. zooms in direction 26 and is controlled via data link 34 bycontrolling means41.

Either of two alternate methods may be used to determine range. Both ofthese methods rely upon superimposition of the target image and themodel image to .form superimposed image 38 on the screen of monitor 14.

In the first method of determining range, television camera is zoomed indirection 26 to create superimposed image 38 appearing on monitor 14. Asecond method of determining range fixes zoom 26 of lens 58 and movescamera 18 in direction 27 to create superimposition of images 38. Inthis second method, range is read out from a linear potentiometer ordigital encoder 60 located at one end of rail 24. Lens 58 is equippedwith an autofocus so that the image of model 19 is always in focus as itappears on monitor 14. Due to optical mismatch which may occur when theflight film is taken with a lens of fixed focal length, the secondmethod of reading out range is preferred over the first.

Read out means30 may be more readily understood by reference to FIG. 2.Range, elevation and azimuth data are received by readout means 30 ondata links 31, 32, and 33, respectively. Scanner 47 performs a switchingfunction whereby range data 31, elevation data 32 and azimuth data 33are alternately scanned, and when potentiometers are used to recordrange, azimuth and elevation, the information is converted into digitalform by digital voltmeter 48. Translator 61 takes the informationderived from digital voltmeter 48 and converts it into a form useable bysummary card punch 49. Summary card punch '49 produces range, elevationand azimuth data for any desired position of model 19 on one punch card.

If encoders are used to provide range, elevation and azimuth data,digital voltmeter 48 is not used, and scanner 47 is connected directlyto translator 61, as the encoders provide digital information whichtranslator 61 can convert into a form useable by summary card punch 49;

The invention described herein may be manufactured and used by or forthe Government of the United States of America for governmentalpurposeswithout the payment of any royalties thereon or therefore.

We claim:

1. A system for determining the orientation of an object in flightcomprising:

means for making a permanent visual record of a particular object inflight;

means for converting the permanent visual record of the particularobject into signals which are capable of being received by a televisionmonitor;

a scale model of the particular object;

means for manipulating said scale model of the particular object inazimuth and elevation;

means for recording the position of said scale model in azimuth andelevation;

means for making a visual record of said scale model, in-

cluding means for converting said visual record of said scale model intosignals which are capable of being received by a television monitor; and

means for determining the range, azimuth and elevation of saidparticular object in flight with respect to the means for making saidpermanent visual record of the particular object in flight, includingmeans for superimposing the visual record of said scale model upon thevisual record of the particular object in flight on the same televisionmonitor.

2. The system of claim 1 wherein:

the means for making a permanent visual record of said object in flightcomprises a movie camera; and

the means for converting said permanent visual record into signalscapable of being received by a television monitor comprises:

a transluscent screen upon which the permanent visual record recorded bythe movie camera is projected by a movie projector;

means for selecting a particular frame of the film in the movie camerafor, projection; and

a television camera for viewing the transluscent screen to convert thepermanent visual record into signals capable of being received by atelevision monitor.

3. The system of claim 2 wherein the means for making a visual record ofsaid scale model comprises a television camera for viewing said modeland producing signals capable of being received by a television monitor.

4. The system of claim 3 wherein:

means are provided formoving the television camera making a visualrecord of the scale model closer to or away form the scale model; meansare provided for recording the distance from the scale model to thefocal plane of the television camera; said television camera is equippedwith a zoorn" lens having multiple focal lengths; means are provided forcalibrating the focal length of the lens as a function of the equivalentdistance from the scale model to the focal plane of the televisioncamera; and means are provided for recording the equivalent distancefrom the scale model to the focal plane of the television camera as afunction of focal length of the zoom" lens. 5. The system of claim 4wherein the means for determining the range, azimuth and elevation ofsaid particular object in flight with respect to the means for makingthe permanent visual record of the object comprises:

means for combining the signals emanating from the television cameraviewing the permanent visual record and the signals emanating from thetelevision camera viewing the model to cause the respective images ofthe permanent visual record and the model to appear on the same monitorscreen; means for moving the image of the model about the televisionraster; means for superimposing the image of the model upon the image ofthe permanent visual record comprising: means for manipulating the modelin azimuth and elevatron; means for moving the image of the model aboutthe television raster; means for moving the television camera viewingthe model 'closer to or away from the model with the zoom lens on thetelevision camera fixed at a predetermined focal length; and means forrotating the television camera viewing the model about its optical axis;means for converting the recorded position of the model so as toindicate the azimuth and elevation of the object in flight with respectto the means for making the permanent visual record of said object inflight; and

means for converting the calibrated distance measurementof thetelevision camera viewing the model to range of the object in flightwith respect to the means for making the permanent visual record of saidobject in flight. 6. The system of claim 4 wherein: Y the means forsuperimposing the image of the model upon the image of the permanentvisual record comprises: means for manipulating the model in azimuth andelevation; 1 means for moving the image of the-model about thetelevision raster; means for changing the focal length of the zoom. lensmounted on the television camera viewing the model with said televisioncamera placed at a predetermined distance from the model; and means forrotating the television camera viewing the model about its optical axis;and the means for determining the range of the object in flight withrespect to the means for making the permanent visual record of saidobject in flight comprises: means for convening the calibrated knownequivalent distance, as read out from the zoom" lens, from the scalemodel to the focal plane of the television camera viewing the model torange of the object in flight with respect to the means for making thepermanent visual record of said object in flight. 7. The system of claim5 wherein:

the means for recordin'g the position of said scale model.

comprises encoding means; and l the means for determining the distancefrom the television camera viewing the model to the model comprisesencoding means. 8. The system of claim 7 wherein: the means ofconverting the'recorded range elevation and azimuth data into the range,azimuth and elevation of the object in flight with respect to the meansfor making the permanent visual record of the object in flightcomprises: a scanner which serially reads the recorded range,

azimuth and elevation data and feeds the serial information totranslating means; translating means which prepare the serialinformation for use by a summary card punch; and a summary card punch tomake a permanentrecord of the range, azimuth and elevation of the objectin flight with respect to the means for making the permanent visualrecord of said object in flight. 9. The system of claim 5 wherein: themeans for recording the position of said scale model comprisespotentiometer means; and the means for determining the distance from thetelevision camera viewing the model to the model comprises linearanalogue potentiometer means. 10. The system of claim 9 wherein: themeans of converting the recorded range, elevation and azimuth data intothe range, azimuth and elevation of the object in flight with respect tothe means for making the permanent visual record of the object in flightcomprises: a scanner which serially reads the recorded analogue range,azimuth and elevation data and feeds the analogue serial information toa digital voltmeter; a digital voltmeter to convert the analogue serialinformation to digital serial information for use by translating,

means;

translating means which prepare the serial information.

